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 0 answersPost by Marian Iskandar on September 4, 2013LOL! "...accidents happen even in the best of families." I will never get bored of his dry wit. Thank you Professor! :))) 4 answersLast reply by: Kamal AhujaFri Feb 3, 2012 3:16 AMPost by Lahdan Rahmati on May 10, 2011At 10:16, he says ox number of hydrogen is +1 THEN at 12:41 he says ox number of hydroden is -1 1 answerLast reply by: Erin MurphyThu Mar 25, 2010 5:32 AMPost by Erin Murphy on March 25, 2010At the 'Oxidation Number Assignment" section, the second example, NH3, you state that H has an oxidation number of -1. I think you meant +1 as you stated in the rules. This would mean that Nitrogen's oxidation number is -3 rather than +3. Please verify this mistake. Thanks!

### Balancing Redox Reactions, Half Reactions

• Oxidation is loss of electrons; reduction is gain of electrons

• Rules for assigning ox. nos. include: elements = 0; H = +1; O = -2; sum of all ox.nos. = charge on species

• Half-reactions are either ox. or red. Will include electrons as reagents – red. half-reaction – or products – ox. half-reaction

• Add appropriate numbers of ox. and red. half reactions to cancel electrons and get whole reaction

• In acid solution use H+ to remove O

• In basic solution use H2O to remove O and make OH-

### Balancing Redox Reactions, Half Reactions

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

• Intro 0:00
• Oxidation and Reduction Review 0:58
• Example: Sodium and Chlorine
• Determining Oxidation Numbers 5:43
• Rules for Assigning Oxidation Numbers
• Oxidation Number Assignment 11:25
• Examples: Various
• Balancing Half Reactions 18:26
• Example: Half Reactions
• Example: Zinc in Hydrochloric Acid
• Combining Half Reactions Into Complete Reactions 24:32
• Example: Zinc
• Spectator Ions
• Half Reactions in Acidic and Basic Solutions 28:38
• Example: Permanganate
• Balancing Redox Reactions 36:34
• Example: Determination of Iron
• Balancing Redox Reactions 45:54
• Example: Lead Dioxide and Chloride Ion